Diazo copy machines utilize ammonia vapor which is brought into contact with diazo dye-coated copy material which has previously been exposed with respect to an original overlaying the same. The ammonia reacts with the diazo dyes to produce a developed print. The process is very useful and is in extremely widespread use, but does have the disadvantage of incidental generation of ammonia odor associated with the operation of the machine and with developed prints.
In an effort to eliminate such odors, machines have heretofore been provided with suction chambers which collect and supply a vacuum to a region adjacent the development chamber and serves to tend to collect the ammonia vapors escaping from the development chamber, as well as given off by the developed copy material. The ammonia vapor containing exhaust from the suction chamber cannot be directly exhausted to the room air, but rather is either exhausted to the outside of the building, or is caused to rise through an ammonia absorbing canister prior to exhaust into the room.
In this latter arrangement, a length of flexible hose or tube is extended from the machine in a position with its outlet beneath the bottom opening formed in the canister. The exhaust thus flows through the absorption canister prior to being returned into the room air.
This arrangement has the disadvantage of necessitating a separate assembly from the machine which must be set up at the installation of the machine and requires additional space for the operation of the machine as well as adding to the cost of set up. In addition, the exhaust from the suction chamber is sometimes merely allowed to be blown generally toward the canister such that some escape of the suction chamber exhaust is possible so that ammonia vapors evacuated from the machine may escape into the surrounding room air.
A problem involved in the use of granular material absorbers in gas purification applications is that of channelization.
Since such canisters sometimes use granular material such as activated carbon granules, channelization will sometimes occur if a horizontal installation were attempted. Such channelization is the formation of low resistance flow paths through the granular material due to crusting of the granular material and the tendency of the flow to occur primarily through these low resistance flow paths.
Such flow of course reduces the operating effectiveness of the unit in removing ammonia vapors due to the resultant reduced, effective quantity of absorbent material available, leading to premature exhaustion of the canister.
Accordingly, it is an object of the present invention to provide a diazo copy machine with an integrated ammonia absorber canister which forms a part of the machine, which can be installed at the assembly of the machine such that the machine requires less floor space and the setting up of the machine for operation is simplified.
It is a further object of the present invention to provide such ammonia absorbing canister installation in which the exhaust from a suction chamber is directed into the absorber canister in such a manner as to preclude the bypassing of any of the suction chamber flow into the room air, while allowing ready assembly of the exhaust tube and canister.
It is still another object of the present invention to provide such an absorber canister including absorbent material with a reduced tendency for the occurrence of channelization.